AUSTIN (AP) – The story line on the Republican Senate race in Texas is a now familiar one: A veteran politician supported by the GOP establishment is challenged by a young insurgent backed by national conservative groups.

In this distinctly Texas episode in the saga for control of the Senate, David Dewhurst is the reserved, self-made millionaire and lieutenant governor facing off against Ted Cruz, the feisty son of a Cuban exile who calls himself “a proven fighter for liberty because his family knows what it means to lose it.”

The underdog is former Dallas mayor and businessman Tom Leppert, who offers himself as the no-nonsense alternative to politics as usual.

Cruz and Leppert acknowledge that Dewhurst is more familiar with voters and has more cash — he’s spent $9.2 million of his $200 million fortune on the primary. But both hope to force a runoff, and if one succeeds, the runner-up could win in July. While there have been no reliable, independent polls in the nine-candidate race, those released by partisans show Dewhurst on the cusp of getting the 50 percent-plus-one he needs to avoid a runoff, with Cruz in second place.

Conservative groups that complain many Senate Republicans now in office are too quick to compromise have spent more than $4 million trying to help Cruz. The benefactors include South Carolina Sen. Jim DeMint’s Senate Conservatives Fund, the anti-tax Club for Growth and former Texas Rep. Dick Armey’s FreedomWorks.

Similar Senate primary battles are taking place in Wisconsin, where tea party favorite Mark Neuman is running against former Gov. Tommy Thompson, and in Arizona, where six-term Rep. Jeff Flake is being challenged by Wil Cardon, who also casts himself as a tea party candidate.

Cruz is drawing comparisons between Texas and Indiana, where state Treasurer Richard Mourdock defeated incumbent Sen. Richard Lugar in the Republican primary. Leppert looks for inspiration from Nebraska, where Deb Fischer, a state legislator, rose up from third place to become the GOP’s Senate nominee there.

Cruz, 41, made his name representing Texas before the Supreme Court in high-profile cases. He has endorsements from former GOP presidential hopeful Rick Santorum and former Alaska Gov. Sarah Palin in addition to several tea party groups.

Dewhurst, 66, has the backing of Gov. Rick Perry and former Arkansas Gov. Mike Huckabee as well as support from the state’s most influential Republican clubs, anti-abortion organizations and political action committees.

There are few significant policy differences between the top three candidates: All oppose abortion rights, amnesty for illegal immigrants and tax increases of any kind. That has forced their campaigns to focus on personality and records with often harsh attack ads.

Tall, reserved and impeccably dressed, Dewhurst was raised by a single mother after his father was killed by a drunken driver. He served in the Air Force and as a CIA officer in Bolivia before returning to Houston, where he started a natural gas business and made his fortune.

Cruz’s father fought against Cuba’s Batista regime in the late 1950s before getting a student visa to attend the University of Texas. Cruz was born in Alberta, Canada, where his dad worked in the oil fields before moving back to Houston. A champion debater, Cruz attended Princeton University and Harvard Law School and has spent most of his career in politically appointed positions in the Bush administration or working for the Texas attorney general.

Leppert, 57, has been CEO of several companies, including the Turner Corp., the nation’s largest construction company. He ran for Dallas mayor as a reformer and balanced the city’s budget.

The competition between Dewhurst and Cruz turned ugly early. Each has spent more than $4 million on TV and radio attack ads.

Dewhurst has derided Cruz as a trial lawyer even though Cruz has specialized in handling appeals. His campaign also pilloried Cruz for representing a Chinese tire company appealing a $26 million judgment that it had stolen intellectual property from a U.S. company. Cruz replied he was only doing his job as an attorney for an international law firm.

Cruz, meanwhile, attacks Dewhurst as a “timid, moderate politician” who too often has compromised with Democrats.

“Enough of these little kitty cats we keep sending to Washington,” Cruz said. “David Dewhurst will compromise every day in the U.S. Senate. … It’s what he’s done every day in state government.”

Boasting about his experience as a top business executive, Leppert calls Dewhurst a career politician and Cruz a government staffer. Dewhurst says Leppert’s record as Dallas mayor is too liberal for Texas Republicans.

Whoever wins the GOP nomination will face one of two Democrats, former state Rep. Paul Sadler and party activist Sean Hubbard. No Democrat has won a statewide office in Texas since 1994.